1. Field of Invention
The present invention relates generally to the field of well bore packing tools (otherwise known as packers), and more specifically to packers deployed using coiled tubing and methods of using same in various oil and gas well operations.
2. Related Art
Packers and plugs are run to hydraulically isolate the sections above and below the packer and to provide a mechanical anchor to prevent the packer from sliding inside the wellbore. In coiled tubing completion applications, the packer also holds the coiled tubing string in place. Packers are set mechanically, hydraulically, or on wireline. The mechanical-set packer is set by applying either tension or compression on the packer. The hydraulic-set packer is activated by hydraulic pressure. A packer forms a seal for purposes of controlling production, injection or treatment. The packer is lowered downhole into the well in an unset state. However, once in the appropriate position downhole, the packer is controlled from the surface of the well to set the packer. As an example, for a mechanically-set packer, a tubular string that extends from the surface to the packer may be moved pursuant to a predefined pattern to set the packer. In its set state, the packer anchors itself to the casing wall of the well and forms a seal in the annular region between the packer and the interior surface of the casing wall. This seal subdivides the annular region to form an upper annular region above the packer that is sealed off from a lower annular region below the packer. The packer typically includes at least one seal assembly to form the annulus seal and at least one set of slips to anchor the packer to the casing string. When run into the well, the seal assembly and the slips are radially retracted to allow passage of the packer through the central passageway of the casing string. After a particular job is complete, the slips and seals are again retracted, allowing the packer to be removed or moved to another location in the well.
Mechanically-set packers currently in use suffer from certain inadequacies. One problem is the inability, after annular fracturing, to cleanup sand and other debris that fall out directly on top of the packer. Fall out may occur when multiple perforation sets are present above the packer. For example, if the proppant fracture from the current zone were to grow vertically and/or poor quality cement is present behind the casing, the fracture could intersect the perforation sets above the packer seal such that proppant could “dump” back into the wellbore on top of the packer and prevent or obstruct further upward movement of the packer. Also, it could be difficult to execute circulation operations if multiple perforation sets are open above the packer. For example, if the circulation pressures exceed the breakdown pressures associated with the perforations open above the packer, the circulation may not be maintained with circulation fluid unintentionally lost to the formation. This may result in a higher probability of sticking the packer in the well.
Thus, there is a continuing need for packers and methods that address one or more of the problems that are set forth above.